Several areas of continued research on the sensitization of human lymphoid cells to antigens on melanoma cells are proposed. Lymphocyte subpopulations will be tested for their ability to be specifically sensitized to autochthonous melanoma cells, and studied with regard to the expression of natural killer (NK) cytotoxicity. A system of T-cell "help" has been investigated, and will now be applied in an attempt to augment the development of cytotoxic effector cells. Secondary sensitization with soluble tumor antigens after in vivo or in vitro priming will be investigated. The sensitization system will be used to study the expression of various melanoma-associated antigens and histocompatibility restrictions on the cytotoxic response.